Prospective exercise examination data for nine thousand employees are being analyzed by multivariate statistical techniques to show the degree of relationship between physical work capacity (PWC 160), oxygen consumption at exercise heart rates of 160 beats per minute and coronary heart disease morbidity in the context of other risk factors (cholesterol, triglycerides, uric acid, hemoglobin, resting and exercise blood pressures, overweight, skinfolds, smoking, age, resting and exercise electrocardiograms, etc). The precise measures of cardiovascular fitness are sensitive to changes in physical activity of ten minutes per day and the reliable ascertainment of cardiovascular events is made possible by complete access to computerized workers' compensation claims files, computerized personnel files, and retirement files.